In the continuing development of optical communication systems, components such as optical amplifiers need to fit into smaller and smaller enclosures (e.g., common form-factor pluggable packages such as CFP, CFP2, CFP4 transceivers and the like). There is limited space for optics and mechanics within these enclosures, thus requiring the included components to be reduced in size as much as possible.
An exemplary one of these CFP enclosures may be required to house a fiber-based optical amplifier that utilizes a spool of erbium-doped fiber as the gain medium. Besides the spool of gain fiber, a typical erbium-doped fiber amplifier (EDFA) includes various input and output fibers (for the input signal and pump signal), as well as other optical fiber-coupled components (e.g., an optical pump source, isolator, and the like). While the optical fibers themselves are small in diameter (e.g., 250 μm), they need to be spliced to one another to complete the optical signal path within the enclosure. In most cases, a fusion splicing process is used to connect a fiber of one component to a fiber of another component. In the fusion process, the end faces of the fibers are heated and “fused” together. Once created, the fusion splice needs to be protected in order to maintain its mechanical strength and environmental integrity. Splice protectors serve to shield the fusion splice from bending and experiencing stress, which may introduce signal loss and ultimately cause the splice to be compromised over time.
Conventional splice protectors are typically made of a flexible, heat-shrinkable plastic, with a small metal bar inside the plastic to create a region of rigidity in the vicinity of the splice. While these commercially available splice protectors have been useful in the past, they are too large in diameter and length to be readily accommodated into the current CFP package designs (and, accordingly, any future enclosures that may be even smaller).
Another option is to overcoat the splice with a polymer that is used to protect the splice. However, these polymer coatings do not necessarily provide adequate mechanical protection and high reliability, especially for small bend conditions as associated with the CFP enclosures.
These aforementioned solutions, especially commercial splice protectors, have been used in the telecommunications industry for many years, but are not adequate for evolving applications.